5 Knowing these things, let us take heed to our life; and let us not be earnest as to the goods that perish; neither as to the glory that goes out; nor as to that body which grows old; nor as to that beauty which is fading; nor as to that pleasure which is fleeting; but let us expend all our care about the soul; and let us provide for the welfare of this in every way. For to cure the body, when diseased, is not an easy matter to every one; but to cure a sick soul is easy to all; and the sickness of the body requires medicines, as well as money, for its healing; but the healing of the soul is a thing that is easy to procure, and devoid of expense.
And the nature of the flesh is with much labour delivered from those wounds which are troublesome; for very often the knife must be applied, and medicines that are bitter; but with respect to the soul there is nothing of this kind. It suffices only to exercise the will, and the desire, and all things are accomplished. And this has been the work of God's providence. For inasmuch as from bodily sickness no great injury could arise, (for though we were not diseased, yet death would in any case come, and destroy and dissolve the body); but everything depends upon the health of our souls; this being by far the more precious and necessary, He has made the medicining of it easy, and void of expense or pain.
What excuse therefore, or what pardon shall we obtain, if when the body is sick, and money must be expended on its behalf, and physicians called in, and much anguish endured, we make this so much a matter of our care (though what might result from that sickness could be no great injury to us), and yet treat the soul with neglect? And this, when we are neither called upon to pay down money; nor to give others any trouble; nor to sustain any sufferings; but without any of all these things, by only choosing and willing, have it in our power to accomplish the entire amendment of it; and knowing assuredly that if we fail to do this, we shall sustain the extreme sentence, and punishments, and penalties, which are inexorable!
For tell me, if any one promised to teach you the healing art in a short space of time, without money or labour, would you not think him a benefactor? Would you not submit both to do and to suffer all things, whatsoever he who promised these things commanded? Behold, now, it is permitted you without labour to find a medicine for wounds, not of the body, but of the soul, and to restore it to a state of health, without any suffering! Let us not be indifferent to the matter! For pray what is the pain of laying aside anger against one who has aggrieved you?
It is a pain, indeed, to remember injuries, and not to be reconciled! What labour is it to pray, and to ask for a thousand good things from God, who is ready to give? What labour is it, not to speak evil of any one? What difficulty is there in being delivered from envy and ill-will? What trouble is it to love one's neighbour? What suffering is it not to utter shameful words, nor to revile, nor to insult another? What fatigue is it not to swear? For again I return to this same admonition.
The labour of swearing is indeed exceedingly great. Oftentimes, while under the influence of anger or wrath, we have sworn, perhaps, that we would never be reconciled to those who have injured us. Yet afterwards, when our wrath was quenched, and our anger allayed, desiring to be reconciled, and restrained by the obligation of these oaths, we have suffered the same anguish, as if we were in a snare, and held fast by indissoluble bonds. Of which fact the Devil being aware, and understanding clearly that anger is a fire; that it is easily extinguished, and that when it is extinguished, then reconciliation and love follows; wishing this fire to remain unquenched, he often binds us by an oath; so that although the anger should cease, the obligation of the oath remaining may keep up the fire within us; and that one of these two things may take place, either that being reconciled we are forsworn, or that not being reconciled we subject ourselves to the penalties of cherishing malice.
Source: Homilies on the Statues (New Advent)